FIG. 1 is a top, front and left side perspective view of a disposable dental handpiece showing our new design;

FIG. 2 is a right side elevation thereof;

FIG. 3 is a left side elevation thereof;

FIG. 4 is a front elevation thereof;

FIG. 5 is a rear elevation thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof;

FIG. 8 is a bottom, rear and right side perspective view thereof;

FIG. 9 is a top, front and left side perspective view of a modified embodiment of the design shown in FIGS. 1 through 8;

FIG. 10 is a right side elevation thereof;

FIG. 11 is a left side elevation thereof;

FIG. 12 is a front elevation thereof;

FIG. 13 is a rear elevation thereof;

FIG. 14 is a top plan view thereof;

FIG. 15 is a bottom plan view thereof;

FIG. 16 is a bottom, rear and right side perspective view thereof;

FIG. 17 is a top, front and left side perspective view of a second modified embodiment of the design shown in FIGS. 1 through 8;

FIG. 18 is a right side elevation thereof;

FIG. 19 is a left side elevation thereof;

FIG. 20 is a front elevation thereof;

FIG. 21 is a rear elevation thereof;

FIG. 22 is a top plan view thereof;

FIG. 23 is a bottom plan view thereof;

FIG. 24 is a bottom, rear and right side perspective view thereof;

FIG. 25 is a top, front and left side perspective view of a third modified embodiment of the design shown in FIGS. 1 through 8;

FIG. 26 is a right side elevation thereof;

FIG. 27 is a left side elevation thereof;

FIG. 28 is a front elevation thereof;

FIG. 29 is a rear elevation thereof;

FIG. 30 is a top plan view thereof;

FIG. 31 is a bottom plan view thereof; and,

FIG. 32 is a bottom, rear and right side perspective view thereof.

The broken lines shown in the drawings are included for the purpose of illustrating environmental structure and form no part of the claimed design.